... the Court finds the FTC has not shown a likelihood it will prevail on its claim this particular vertical merger in this specific industry may substantially lessen competition. To the contrary, the record evidence points to more consumer access to Call of Duty and other Activision content. The motion for a preliminary injunction is therefore DENIED.
According to this article, in the US, it looks like 1982. It was AT&T. But it looks like they are currently trying to break up Meta.
I thought Microsoft had split too, but they mention that in the article and say they never actually split. I thought Intel was also split at one point, but it's not listed here, so I'm probably wrong.
Microsoft lost an antitrust lawsuit a long time ago regarding making internet explorer a required part of Windows, so they had to allow other browsers in Windows for competition's sake, but they didn't get broken up. That might be what you are thinking of. I can't think of anything Intel related though.
Antitrust suits result in more varied options than just breaking a company up. Microsoft had to have certain aspects of it's operations supervised by the Department of Justice for years, and had to make mandatory changes with respect to browser bundling that only ended with Windows 10/11.
Intel has settled some antitrust actions -- namely lawsuits by AMD -- with money and cross-licensing agreements. They've spun off some divisions and operations over the years but none forced that I can recall.
I'm pretty sure there's like 3 companies that own around 80% of the US grocery market. There's a reason why avian flu drove the price of eggs up everywhere and its because one company owns the majority of egg production.